130 EURETE ERECTUM. 



times that the spines were arranged in elongate spiral rows; in other cases no such 

 spiral arrangement could be made out. Often the spines are restricted to the 

 distal and lateral sides of the rays ; sometimes, however, they are also found on 

 the proximal side. 



The irregular gastral pinule-derivates (Plate 30, fig. 3) are similar to the regu- 

 lar pentactine-like ones and differ from them only in one or two of their lateral 

 rays resembling the distal rays of pinules. 



The uncinates (Plate 31, figs. 13, 14) are slightly curved or nearly straight, 

 pointed at both ends, 0.5-1.6 mm. long, and 4-9 yu thick. Their spines are 7-27;u 

 long, and 0.6-1 n thick at the base. They either diverge considerably (Plate 31, 

 fig. 14) or are nearly parallel to the shaft (Plate 31, fig. 13). Their tips are 1.5- 

 4 ju distant from the shaft. This elevation of their tips is by no means always in 

 proportion to their length. 



The discohexasters (Plate 31, figs. 15, 18, 21) measure 50-70 m in total 

 diameter. Their main-rays are regular, smooth, straight, 6-10 ^ long, and 1.0- 

 3 IX thick. Each main-ray bears from one to four end-rays. These are usually 

 curved, concave to the continuation of the main-ray at the base, and nearly 

 straight farther on. They are 18-26 /j long, 1.2-2 n thick at the base, and 

 attenuated distally to 0.8-1.5 n. The end-rays bear along their length minute 

 recurved spines, and at the end a terminal verticil of similar but larger spines, 

 which together form a kind of terminal disc with deeply serrated margin 2.5-4 m 

 in transverse diameter. 



It is possible that there are two kinds of discohexasters similar in size, but 

 differing in respect to the end-rays, one with more slender and less spiny, the 

 other with stouter and more spiny end-rays. Since, however, these asters are 

 scarce I was unable to decide whether they all belong to the same series of forms, 

 or whether two distinct varieties of them, as indicated above, should be distin- 

 guished. 



The dermal scopules (Plate 31, figs. 16b, 17, 19) are 200^20 ^ long and 

 consist of a centrum 4-10 ^ long and 5.5-1 1 .5 ^ broad, from which arises at one end 

 (the inner) a simple shaft, and at the opposite (the outer) a bunch of end-rays. 

 The centrum is not well-defined, often it passes quite gradually into the 

 shaft. It and the proximal part of the shaft are densely covered with minute 

 spines. The shaft is straight, cylindroconic, 170-330 fx long, 3-6 yu thick at the 

 base, and pointed at the end. Sometimes, particularly in the dermal scopules 

 with only two end-rays, this spinulation extends quite to the end of the shaft. 

 Some of the dermal scopules have four end-rays, others only two, and a few have 

 three. The dermal scopules with only two end-rays are fork-Uke. The end-rays 



